Air-cooling apparatus



March 12, 1946. E. J. DlLLMAN AIR COOLING APPARATUS Filed March 13, 1944FIG. 2

KIE owmDtQmulvzu JON-P200 MO52- OUTSIDE TEMPERATURE FAHR.

INVENTQR BY QMM KM M ATTORNEY Patented Mar. 12, 1946 UNITED STATEAIR-COOLING APPARATUS .Earnest J. Dillman, DetroitfMicln, asslgnor toDetroit Lubricator Company, Detroit, Mich.,

a corporation of Michigan Application March 1944, Serial No. 526,229

4 Claims.

This invention relates to new and useful improvements in apparatus forcomfort cooling the space in a vehicle or automotive bus to be occupiedby human beings.

An object of the invention is to cool the space a Another object is tocontrol the speed of the en- I gine in accordance with a differentialbetween the temperatures inside and outside of the space as the outsidetemperature increases,'but at a less rate than the rate of increase ofthe external Fig. 2 is a temperature chart showing the relation oftemperatures within and outside of the bus, as maintained by" thecontrol means of Fig. 1.

Referring to thedrawing by characters of reference, l designates thebody of a bus having a space 2 to be occupied by the bus passengers andwithin which is positioned an air cooling coil or refrigerant mediumevaporator 3 forming the low side of a refrigerating apparatus. Thesupply of refrigerant medium to the evaporator 3 is controlled by theusual thermostatic expansion valve 4 intercalated in the refrigerantmedium liquid line 5 and having a temperature responsive control bulb 6clamped to the'refrigerant medium return or suction line 1. The liquidline 5 is fed from a tank or receiver 8 positioned external of the space2 and mounted within the housed space 8 of a supporting structure. It.The receiver 8 is fed from a condenser l I contained in the space 9 andconnected by a feed line l2 to the outlet of a compressor l3 which hasits inlet connected to the return line 1. The compressor I 3 is drivenby belt or other gearing l4 from an internal combustion engine l5 havinga carburetor l6. The supply of fuel mixture from the carburetor It tothe engine I5 is controlled by a throttle valve l1 operated by a link l8pivotally connected to a lever it which is pivotally connected tothermostatically operated thrust members 20, 2|. The

thrust member 20 is operable by'the movable wall, such as a metalbellows, of an expansible, contractible chambered member 22 connected bya capillary tube 23 to a bulb element 24. The bulb elemeni 24, tube 23and theexpansible, contractiible chamber-in member 22 are charged solidwith a temperature responsive expansible liquid such, for example, askerosene, so that the rod 20 will be moved in accordance withtemperature change to which the bulb element 24 is subjected. The rod 2|is operable by the movable wall, such as a metal bellows, of anexpansible, contractible chambered element 25 connected by a capillarytube 26 to a bulb element 21 mounted within the space 2 adjacent theexternal location of the bulb element 24, so that the bulb elements 24and 21 are in side by side relation separated by the bus wall and sothat the capillary tubes 23 and 26 will be of substantially equallength. The bulb element 21, tube 28 and the expansible, contractiblechamber of the member 25 are charged solid with the same temperatureresponsive liquid as in the element 24, namely kerosene. The volumetriccapacity of th bulb element 21 is so related to the volumetric capacityof the bulb 24 that when the tubes 23 and 26 and the chambered member 22and 25 are of equal capacity, the relative expansion of the liquids inthese bulb elements will give f the curve shown by the chart of Fig. 2,that is, the volumes of the elements 24 and 21 will be proportional tothe ordinate and the abscissa respectively of the tangent of thetemperature curve. The 7 tubes 23 and 26 are maintained in closeproximity-to each other throughout-their lengths so that they will besubjected equally to any changes oftemi erature and also to the sametemperatures 50' that the valve l1 will be controlled substantiallysolely by the differential of expansion of the liquids in the bulbelements 24 and 21. The thrust members 20 and 2| are connectedrelatively close to each other to the lever I! so that a temperaturechange of say 3 F. at the bulb element 21 will move the throttle valve Hfrom full open to full closed position or vice versa. The bulbelemeat 24then operates to control the range or to determine the temperaturesetting at which the bulb element 21 operates the throttle valve I1.

The operation of this apparatus is as follows:

With the refrigerating apparatus in operation, the compressor [3 beingdriven by the engine l5 and the expansion valve 4 maintaining theevaporator 3 refrigerated throughout its length, the throttle valve I1will be automatically adjusted to regulate the engine speed andtherefore the speed of the compressor l3 and resulting low side orevaporator pressure. -If the temperature within the space 2 due toincrease in the number of pas-.

sengers increases, then the bulb element 21 responding to thetemperature increase will rotate the lever I! on the rod 20 as a fulcrumand move 3 to counteract the temperature increase in the.

space 2. Decrease of temperature in the space 2 will correspondinglyrotate the lever I! in the reverse direction to decrease the speed ofthe engine II and therefore of the compressor i3 so that the rate ofheat absorption by the evaporator 3 will be reduced. The bulb element 24will also function to operate the lever I9 but, being of smallercapacity, will act to a lesser degree than the bulb 21 such that upondecrease in .external temperature the throttle valve II will be movedtoward open position by the lever i9 fulcrumins on the rod 2|. Whenthere is an increase in outside temperature, the liquid in bulb element24 will exert its expansion pressure to move the throttle valve lltoward closed position, so that the inside bus temperature will bepermitted to increase in order to maintain the straight line temperaturedifferential. Accordingly, the bulb elements 2 and 21 will act, asoutside temperature increases, to maintain a predetermined increasingtemperature differential between the interior and the exterior ofthespace 2, balancing the speed of the engine I! in relation to thedifferential at a given outside temperature, and accordingly balancingthe rate of heat absorption by the evaporator I.

What is claimed and is desired to be secured by Letters Patent f theUnited States is:

l. A cooling apparatus for buses comprising a bus body having anenclosed space for human occupancy, a supporting structure external ofsaid space, a refrigerating apparatus having a condenser and compressormounted on said supporting structure and having a refrigerant mediumevaporator positioned in said space, an internal combustion enginegeared to and for driving said compressor and mounted on said structure,a throttle valve controlling the speed of said engine, and differentialtemperature responsive means controlling said throttle valve inaccordance with a desired difference-between the temperatures within andexternal of said space, said responsive means being so proportioned andrelated to each other that the temperature in said space increases at aless rate than the rate of temperature increase external of said space.

2. A cooling apparatus for buses comprising a bus body having anenclosed space for human ternal combustion engine geared to and fordriving said compressor and mounted on said structure, a throttle valvecontrolling the speed of said engine, a pair of chambered members eachhaving a movable wall, thrust rods movable one by each of said walls. alever pivotally connected to and supported bysaid rods and operativelyconnected to said valve, each of said rods serving as a fulcrum foroperation of said lever by the other of said rods, capillary tubesconnected one to each chambered member and each having a bulb element,said chamberedmembers, tubes and elements being charged solid with anexpansible liquid, one of said bulb elements bein positioned in saidspace and having a greater volumetric capacity than the other-of saidelements, and said other. element being mounted external of said spaceso that said throttle valve is moved toward open position in accordancewith an increasing differential between the temperatures within andexternal of said space as the temperature external of said spaceincreases.

ing said compressor and mounted on said struc-- ture, a throttle valvecontrolling the speed of said engine, a pair of chambered members eachhaving a movable wall, thrust rods movable one by each of said walls, alever pivotally connected to and' supported by said rods and operativelyconnected to said valve, each of said rods serving as a fulcrum foroperation of said lever by the other of said 'rods, capillary tubesconnected one to each chambered member and each having a bulb element,said chambered members, tubes and elements being charged solid with anexpansible liquid, one of said bulb elements being positioned in saidspace and having a greater volumetric capacity than the other of saidelements, said other element being mounted external of 'said space sothat said throttle valve is moved toward open position in accordancewith an increasing differential between the temperature within and thetemperature external of said space as the temperature external of saidspace increases, and said capillary tubes being of substantially equallength and extending in close proximity to each other-from said bulbelements to said chambered members so that the expansion of the liquidin said tubes will be substantially equal.

4. A cooling apparatusfor buses comprising a bus body having an enclosedspace for human occupancy, a refrigerating apparatus having arefrigerant medium evaporator positioned in said space and having acompressor and a condenser operatively connected together and tosaidevaporator, means for driving said compressor at avariable speed, a pairof chambered members each having a movable wall, thrust rods movable oneby each of said walls, means controlling the speed of said drivingmeans, a lever pivotally connected to and supported by said rods andoperatively connected to said controlling means, capillarytubesconnected one to each of said chambered members and eachtube-having a, bulb element, said chambered members, tubes and elementsbeing filledwith expansible medium, one of said bulb elements beingpositioned insaid space and having a greater volumetric capacity thanthe other of said elements, the said other of said elements beingmounted external to' said space so that said controlling means isoperated to increase the speed of said driving means in accordance withan increasing differential between the temperature within and thetemperature external to said space asthe temperature external to saidspace increases, and said capillary tubes being of substantially equallength and extending in close proximity to each other, from saidelements to said chambered members so that the total linear expansion ofthe expansible mediums in said tubes will be substantially equal.

EARNIBT J.

